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GCN Circulars

GCN Circulars are rapid astronomical bulletins submitted by and distributed to community members worldwide. They are used to share discoveries, observations, quantitative near-term predictions, requests for follow-up observations, or future observing plans related to high-energy, multi-messenger, and variable or transient astrophysical events. See the documentation for help with subscribing to or submitting Circulars.

Search for Circulars by submitter, subject, or body text (e.g. 'Fermi GRB').
To navigate to a specific circular, enter the associated Circular ID (e.g. 'gcn123', 'Circular 123', or '123').
Advanced Search

To narrow the search results, use advanced search syntax. This allows for specifying which circular field to search (submitter, subject, and/or body). For additional information, refer to the advanced search documentation.

Advanced Search Examples (click to copy):

subject:"Swift"
body:"GRB"
submitter:"Judith Racusin"

25989 results found.

  1. GRB 251025B: MASTER OT detection
  2. GRB 251025B: SVOM/C-GFT optical counterpart detection
  3. GRB 251025B: SVOM detection of a burst
  4. GRB 251025A (sb25102501): Likely a stellar flare by SVOM/VT
  5. GRB 251025A: SVOM/COLIBRÍ (FM-GFT) optical upper limit
  6. GRB 251025A: SVOM/VT VHF optical upper limit
  7. GRB 251025A: SVOM detection of a faint burst
  8. GRB 251003A: VLA Detection
  9. GRB 251024A: Enhanced Swift-XRT position
  10. GRB 251023C: Glowbug gamma-ray detection
  11. GRB 251024A: LCOGT Optical Afterglow Detection
  12. GRB 251022A: KAIT optical observations
  13. GRB 251024A: Swift detection of a burst
  14. GRB 251023B / EP251023b: COLIBRÍ Confirmation of the Fading Nature of the Optical Candidate
  15. GRB 251022A: COLIBRÍ Further Multi-frequency Optical Observations
  16. EP251023a: MAO/AZT-22 optical observations
  17. GRB 251023C: AstroSat CZTI detection
  18. EP251023b/GRB 251023B: JinShan optical observation
  19. GRB 251022A: Swift-XRT detection of GOTO25iym
  20. EP251023b/GRB 251023B : Einstein Probe detection of a fast X-ray transient
  21. GRB 251022A: GROWTH-India Telescope optical observations
  22. GRB 251023C: Swift/BAT-GUANO localization skymap of a burst
  23. EP251023a: GROWTH-India Telescope optical observations
  24. GRB 251022A: Fermi GBM Observation
  25. GRB 251022A: Swift/BAT-GUANO localization skymap of a burst
  26. GRB 251023A: Glowbug gamma-ray detection
  27. GRB 251023B: Glowbug gamma-ray detection
  28. EP251023a: ULL-ASTRO-MASTER detection of the optical afterglow with LCO 40-cm telescope at Teide Observatory
  29. GRB 251023B / EP#01709247298: COLIBRÍ optical counterpart candidate
  30. IPN triangulation of GRB 251016B
  31. EP#01709247298: Swift-XRT counterpart detection
  32. EP251023a: COLIBRÍ optical observations
  33. GRB 251013C: further SAO RAS optical observations
  34. GRB 251022A: COLIBRÍ optical observations
  35. GRB 251013C: ISON-Castelgrande observatory optical observations
  36. GRB 251022A: MASTER OT detection
  37. GRB 251022A: DDOTI Optical Detection
  38. EP251021b/GRB 251021A: SVOM/VT optical candidate
  39. GRB 251023B / MAXI J0451+122: MAXI/GSC detection
  40. EP251023a: NOT optical counterpart detection
  41. EP251023a: GSP Optical Counterpart Detection
  42. EP251023a: Einstein Probe detection of an X-ray transient
  43. GRB 251016B: Fermi GBM Detection
  44. GRB 251021A/EP251021b: Fermi-GBM Sub-Threshold Detection
  45. EP251021b: Einstein Probe detection of a fast X-ray transient
  46. LIGO/Virgo/KAGRA S251021u: Updated Sky localization
  47. LIGO/Virgo/KAGRA S251021u: Identification of a GW compact binary merger candidate
  48. LIGO/Virgo/KAGRA S251018bi: Updated Sky localization
  49. Fermi-LAT gamma-ray observations of IceCube-251018A
  50. GRB 251017A : RAPAS follow-up observations
  51. IceCube-251018A: Upper limits from a search for additional neutrino events in IceCube
  52. GRB 251017A: COLIBRÍ optical observations of a late plateau
  53. IceCube-251018A: DDOTI Optical Upper Limit
  54. GRB 251017A: Swift-BAT refined analysis
  55. GRB 251018A: Fermi GBM Observation
  56. GRB 251018A: BOOTES-5 and BOOTES-7 early optical detections
  57. GRB 251018A: Swift-XRT refined Analysis
  58. GRB 251018A: Enhanced Swift-XRT position
  59. LIGO/Virgo/KAGRA S251018bi: Identification of a GW compact binary merger candidate
  60. GRB 251016A: Swift-XRT afterglow detection
  61. GRB 251017A: Swift/UVOT Detection
  62. GRB 251016A: Swift/UVOT Detection
  63. GRB 251018A: Swift/UVOT Detection
  64. GRB 251016A: VLT/FORS2 Optical Observation
  65. GRB 251017A: COLIBRÍ photometric redshift
  66. GRB 251017A: Swift-XRT refined Analysis
  67. GRB 251018A: MASTER OT detection
  68. GRB 251018A: TRT optical afterglow detection
  69. GRB 251018A: Swift detection of a burst with an optical counterpart
  70. GRB 251011A: Fermi GBM Observation
  71. GRB 251017A: J-band detection with WINTER
  72. GRB 251017A: Glowbug gamma-ray detection
  73. GRB 251013C: Liverpool Telescope observations
  74. GRB 251013C: Leavitt Observatory optical photometry
  75. GRB 251017A: JinShan observations of the optical afterglow
  76. GRB 251017A : MITSuME Akeno optical afterglow candidate detection
  77. GRB 251016A: AstroSat CZTI detection of a short burst
  78. GRB 251017A: Enhanced Swift-XRT position
  79. GRB 251017A: COLIBRÍ Early Afterglow Detection
  80. GRB 251017A: BOOTES-5/JGT early optical afterglow detection
  81. GRB 251017A: Swift detection of a burst with an optical counterpart
  82. GRB 251013C: JinShan observations of the non-thermal rebrightening of the optical counterpart
  83. GRB 251013C: SVOM/COLIBRÍ (FM-GFT) observations of a strong and late rebrightening of the optical counterpart
  84. GRB 251007B: Swift-BAT refined analysis
  85. GRB 251014D: Swift-BAT refined analysis
  86. GRB 251016A: BOOTES-6/DPRT optical upper limit
  87. GRB 251016A: Glowbug gamma-ray detection of a short burst
  88. sb25101602: Swift-XRT counterpart detection
  89. GRB 251014A: Swift-XRT observations
  90. LIGO/Virgo/KAGRA S251014cn: Updated Sky localization
  91. GRB 251014B: PRIME J-band upper limit
  92. Upper limits from a search for additional neutrino events in IceCube
  93. IceCube Alert 251014.77: Global MASTER-Net observations report
  94. GRB 251013C: Kilonova-Catcher optical afterglow detection
  95. Fermi-LAT Gamma-ray Observations of IceCube-251014A
  96. GRB 251013D: Swift/UVOT Observations
  97. GRB 251013C: Swift/UVOT Detection
  98. GRB 251013C: detection of a radio counterpart at 15.5GHz
  99. GRB 251013D: Swift-XRT observations
  100. Swift Trigger 1404295: possible GRB 251015A

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